Standout electrochemical performance of SnO2 and Sn/SnO2 nanoparticles embedded in a KOH-activated carbonized porous aromatic framework (PAF-1) matrix as the anode for lithium-ion batteries

Attributed to their high specific capacity and safe working potential versus Li/Li+ as compared to commercial graphite anodes, tin and tin oxide have received widespread attention as promising anode materials for Li-ion batteries, whereas they also suffer from some drawbacks, such as large volume expansion and poor electrical conductivity during the lithiation/delithiation process. To address these issues, a series of composites with ultrasmall Sn and SnO2 nanoparticles (6-15 nm) embedded in a KOH-activated carbonized porous aromatic framework (PAF-1) matrix as anode materials were prepared by adjusting the Sn2+ content and carbonization temperature. Attributed to its high microporosity and electrical conductivity, the KOH-activated carbonized PAF-1 is a potential host matrix to cogently solve the problems of pulverization, metal aggregation and loss of electrical contact with the electrode over repeated cycling. The synergy between SnOx and the carbon matrix is manifested by the outstanding capacity and stability of the material, which owes its standout features to the SnOx nanoparticles located inside the micropores of the carbon matrix. Of all the materials, SnOx@K-PAF-1-750-25 prepared by optimizing the contents and preparation conditions showed excellent stability and cycling performance, retaining a capacity of 608 mA h g(-1) over 400 charge/discharge cycles even at a high current density of 400 mA g(-1).